Observations of Ice and Its Sediments on the Baltic Sea Coast

Ice samples were taken in winter 1996 for determining the quality and quantity of sediment inclusions (suspended matter). The study area was the coast of the Gulf of Finland in the Baltic Sea. The data are from 13 sites and include for the water fraction of a melted ice sample pH, electric conductivity and soluble matter, and for the suspended matter within the ice include the total mass, organic proportion and concentrations of some chemical elements. Three lakes were sampled for regional freshwater references. The soluble matter was mainly due to the salts in sea water and amounted to around 1 g/l (25-50% of the water salinity), and the pH was 4.0-7.5. The sediment content was mostly 1-10 mg/l; larger values resulted from industrial and traffic fallout on ice and snow and from sea bottom sand. Of toxic metals, lead and zinc showed enriched concentrations in ice and snow. The snow cover was also investigated and the result was close to those of the ice samples, but the pH and amount of soluble matter was lower in the snow. A potential ecological risk exists in spring as the ice and snow meltwater, with possibly a very low pH and enriched in pollutants, is mixed with the surface water layer. This layer is particularly thin beneath the fast ice zone.